Lock



Jill) 31, 1934. J. A HORNE 1,968,555

LOCK

Filed Feb. 19, 1927 Patented July 31, 1934 Look Joseph A. Horne,Stamford, Conm, assignor to. The Yale& Towne Manufacturing Company,

Stamford, Conn.

Application February 19,1927, Serial No. 169,519 16 Claims. (oi. 70-46)This invention relates to improvements in looks and more particularly tothose of the cylinder. type; the improvements being especially valuablewith a die cast plug which is brittle and 5 easily broken.

The object of the present invention is to proyide a cylinder lock whichcannot be surreptitiously operated, and, more specifically, to provide aconstruction of lock whereby an attempt toopen the look by the use ofaninstrumeiit, other than the key provided therefor, will render thelock inoperative without retracting the bolt. A further object of theinvention isto plug will be fractured and no movement imparted to thebolt-throwing cam when an attempt is made to operate the lock bythefluse of a screw driver or similar implement. A structure embodyingthe invention is illustrated in the accompanying drawing and will behereinafter fully described, the invention residing in certain novelfeatures which will be particularly pointed out in theappended claims. f

In the drawing, Figure 1 is a longitudinal section of'so much of acylinder lock as is necessary to an understanding of the invention,

Figure 2 is an elevation of the. outer end of the lock, l

Figure 3' is a simila'rview of the inner end of the lock,

Figure 4 is a longitudinal section in a plane at a right angle to theplane of Figure 1,

Figures 5 and 6 are transverse sections on the lines 5--5 and 6--6,respectively, of Figure 1,

Figure 7 is a plan view of the plug,

Figure 8 is a longitudinal section of the cylinder free of the plug andthe cam,

Figure 9 is a plan view of the cam.

The cylinder 1 receives the cam 2 in its inner end and the plug 3 in itsouter end. The cylinder is provided adjacent its ends with internalannular grooves 4 4 the latter receiving a snap ring 5 which seats in amating groove 6, in the cam. A groove '7 in the plug mates with thegroove 4, and a locking wire 5 inserted through a tangential hole in thecylinder wall, occupies the mating grooves 4-4 to lock the plug againstlongitudinal movement, as disclosed in pending application filed byMaxwell C. Maxwell and 5'0" designated by Serial No. 126,556. Thecylinder is also provided with a stop flange 8 near its outer end whichis engaged by a lug 9 on the plug head 10 to limit the rotary movementof q the plug.

According to the present invention, the die provide a cylinder andtumbler lock in which thecast plug 3 is of differential formation, theouter portion .11 being of greater diameter than the inner portion 12,as clearly shown in Figures 4 and {7. The plug is formed with the usualkeyway' 13 and tumblers 30 are mounted in the plug and engaged with thecylinder in the usual manner, three tumblers being carried by the innerweaker portion 12 and two tumblers being carried by the outer relativelystronger portion 11. The cam is formed with the spaced arms 14projecting from its head, and these arms are of such length and producedon such a radius that they fit closely over the inner reduced portion 12of the plug, at the sides-of the keyway and thetumblers therein, but donot extend over the portion 11 thereof, the three tumblers carried inthe inner smaller portion of the plug serving to actuate the cam whenthe lock is operated by the key;

Under normal operation of the lock, no strain isput on the plug as allthe strain of operating the cam-i-s;borne by the key and the tumblers;Should a flat blade; such as ascrewdriver, be inserted in the plugand'an attempt be made to rotate the plug, the effort to effectrotationwill 30 be resistedby the tumblers and the plug will be fractured atthejuncture-of its larger and small er portions. Application of therotative force will also shear thetwo tumblers carried by the outerstronger portion of the plug which will 55 then rotate'independently ofthe inner weaker portion, the latter and its tumblers retaining the camin locked position.

Having fully described my invention what I 1;; claim as new and desireto secure by Letters Patent, is:- 4

1. A plug for cylinder locks having its outer portion relatively strongand an inner relatively weak portion whereby said outer portion may bebroken from the inner portion under rotative force and tumblers carriedby both of said portions.

2. A die cast plug for cylinder locks having relatively weak and strongportions, tumblers carried by each of said portions, the juncture ofsaid portions being denoted by an abrupt structural change, wherebybreakage at said juncture will be facilitated when said plug issubjected to strain.

3. A plug for cylinder locks having its inner portion of less diameterthan its outer portion 3,. whereby the plug may be fractured underabnormal strain and locking tumblers mounted in each of said portions.

4. A sliding tumbler lock comprising a plug having relatively strong andweak portions, tumblers carried in each of said portions, a sleevecarrying a cam and mounted on the weak portion of the plug and adaptedto be actuated by the tumblers carried in said weak portion.

5. A look comprising a plug having relatively strong and weak sections,cam mechanism carried by the weak section, tumblers carried by each ofsaid sections, the tumblers of the weak section being adapted to actuatethe cam mechanism carried by said weaker section.

6. The combination of a cylinder lock plug, and a cam having spaced armsprojecting over the inner end of the plug.

'7. The combination of a plug having an inner end portion of lessdiameter than its outer end portion, and a cam having spaced armsengaging about the smaller end portion of the plug.

8. The combination of a lock cylinder, a frangible plug rotatably heldin one end of the cylinder, and a cam rotatably held in the other end ofthe cylinder and engaging around the inner end of the plug.

9. The combination of a lock cylinder, a plug rotatably mounted in oneend of the cylinder, tumblers mounted in the plug and normally engagingthe cylinder, and a cam rotatably mounted in the opposite end of thecylinder and having elements fitting about the plug at the sides of someof the tumblers.

10. The combination of a lock cylinder, a plug rotatably mounted in saidcylinder and having its inner end of less diameter than its outer end,tumblers mounted in the forward end of the plug and normally engagingthe cylinder, and a cam rotatably mounted in the cylinder and havingelements fitting between the cylinder and the smaller end of the plug atthe sides of the tumblers therein whereby effort to rotate the plugwithout releasing the tumblers from the cylinder will fracture the plugbetween its ends and shear the tumblers in its outer end.

11. A look comprising a plug, and a group of tumblers carried thereby, asleeve carrying a cam mounted on said plug, but freely rotatablerelatively thereto, certain of said group of tumblers being adapted toactuate the cam sleeve when the lock is operated.

12. In a cylinder lock, a plug, and a bolt-throwing cam having plugengaging arms, said cam being loosely mounted on the plug.

13. In a lock device including a casing, 21. cylinder rotatable withinthe casing and having a key receiving opening and tumblers carried bythe cylinder to normally look the same in the casing against rotation,said tumblers being operable by the insertion of a proper key in thecylinder opening to permit rotation of the cylinder, a tail piece havinga flange to be received in the casing from the rear, a spring ringengageable in a groove in the casing and in a groove of said tail pieceflange to secure the same within the casing, and an operative connectionbetween the tail piece and cylinder.

14. A plug for cylinder locks having a head portion, a relatively strongportion and a relatively weak portion, tumblers carried by said weak andstrong portions, said strong and weak portions being arranged so thatthe plug may be easily ruptured at the juncture of said portions uponattempted rotation with a tool other than its own key.

15. A plug for cylinder locks having forward and rearward tumblercarrying portions, said portions being defined from each other by adistinct structural change, tumblers in each of said portions to resistturning movement of said plug in a cylinder except when said tumblersare properly positioned by a key, the tumblers in said forward portionbeing more readily severable than the rearward portion tumblers whenstress is placed on the forward portion of said plug to rotate the samewithout proper positioning of the tumblers, whereby said forward portionand its tumblers will readily be severed from said rearward por tion bysuch surreptitious operation.

, 16. A plug for cylinder locks having forward and rearward tumblercarrying portions, said portions being defined from each other by adistinct structural change, tumblers in each of said portions to resistturning movement of said plug in a cylinder except when said tumblersare properly positioned by a key, the tumblers in said forward positionbeing fewer in number than those in the rearward position so as to bemore readily severable than the rearward portion tumblers when stress isplaced on the forward portion of said plug to rotate the same withoutproper positioning of the tumblers, whereby said forward portion and itstumblers will readily be severed from said rearward portion by suchsurreptitious operation.

JOSEPH A. HORNE.

